Question

I’ve been trying to create web app in Ruby on Rails, which would collect menu for different restaurants and show it in my app. I’d like to create many-to-many association, but I’m a little confused there. I’ve googled many-to-many relationship and read about HABTM or has_many/belongs_to, still a bit confused.
My classes:

restaurant = {name}

menu = {name, price}

And join table:

menu_restaurant = {date}

I’m confused here. I’ve read that I can’t use HABTM with extra values in join table. And also I should not have model for join table using HABTM.

My current models:
app/models/menu.rb

class Menu < ActiveRecord::Base
  attr_accessible :cenaStudent, :name
  has_many :restaurants, dependent: :destroy
  validates :priceStudent, presence: true
  validates :name, presence:true
end

app/models/restaurant.rb

class Restaurant < ActiveRecord::Base
  attr_accessible :name
  has_many :menus, dependent: :destroy

  validates :name, presence: true 
end

app/models/menu_restaurant.rb

class MenuRestaurant < ActiveRecord::Base
  attr_accessible :date
end

and these are my db tables
db/migrate/{timestamp}_create_restaurants.rb and similar {…}menu.rb

class CreateRestaurants < ActiveRecord::Migration
  def self.up
    create_table :restaurants do |t|
      t.string :name

      t.timestamps
    end
  end

  def self.down
    drop_table :restaurants
  end
end

db/migrate/{timestamp}_create_menus_restaurants.rb

class CreateMenusRestaurants < ActiveRecord::Migration
  def up
    #create the association table
    create_table :menus_restaurants, :id => false do |t|
      t.integer :menu_id, :null => false
      t.integer :restaurant_id, :null => false
      t.date :date
    end

    #add index
    add_index :menus_restaurants, [ :menu_id, :restaurant_id]

  end

  def down
    remove_index :menus_restaurants, :column => [ :menu_id, :restaurant_id]
    drop_table :menus_restaurants
  end
end

What relationship in ruby on rails whould I use? What models do I need?

And I have a second question related RoR MVC architecture. I am going to write it here since it’s related.

I created a function in ruby that downloads pdf file containing menu list. Parses menu name and price. Restaurant name is matched with pdf file. So I have data I need to insert them into db. How do I do that and where? I guess some parts should be in controller and function should be in lib directory? It’s my first app using any architecture.
It’s also my first stackoverflow question, hope I didn’t forget anything.

Answer 1

I think you are almost there, your migrations and models seem ok except for dealing with the join table :menu_restaurants.

I have altered your models for so that the join table hooks everything up

class Menu < ActiveRecord::Base
  attr_accessible :cenaStudent, :name
  has_many :menu_restaurants
  has_many :restaurants, through: :menu_restaurants , dependent: :destroy
  validates :priceStudent, presence: true
  validates :name, presence:true
end

class Restaurant < ActiveRecord::Base
  attr_accessible :name
  has_many :menu_restaurants
  has_many :menus, through: :menu_restaurants , dependent: :destroy
  validates :name, presence: true 
end

class MenuRestaurant < ActiveRecord::Base
  attr_accessible :date
  belongs_to :menu
  belongs_to :restaurant
end

Also I think your join table should be called menu_restaurants (singular on the word menu)